Work on nested list support for ordered and unordered lists.

Work on nested list support for ordered and unordered lists.

* lisp/muse-publish.el: Nested list support isn't quite finished, but
  progress is being made.
  (muse-publish-markup-regexps): Remove 2150 regexp since it doesn't seem
  useful at the moment.  Invoke `format' to get the general version of
  muse-list-item-regexp.
  (muse-publish-surround-text): Add INDENT argument that specifies the
  leading indentation to strip.  Default is all whitespace.  Loop until
  MOVE-FUNC returns nil.
  (muse-list-item-type): New function that figures out what kind of list
  we have, given its separator string.
  (muse-forward-paragraph): Make this slightly more general.
  (muse-forward-list-item): New function that moves forward to the next
  list item.  Non-nil is returned if we found another item of the same
  type, nil otherwise.
  (muse-publish-markup-list): Adapt unordered list and ordered list to
  perhaps do nested lists correctly, though this hasn't been tested.

* lisp/muse-regexps.el (muse-list-item-regexp): Use "%s" in place of
  initial whitespace for the sake of flexibility.  Call `format' on it to
  change it.
git-archimport-id: mwolson@gnu.org--2005/muse--main--1.0--patch-326